DEVELOPMENT OF COMPUTATIONAL WEAR PREDICTION ON

TOTAL ANKLE REPLACEMENT

AMIR PUTRA BIN MD SAAD

UNIVERSITI TEKNOLOGI MALAYSIA

DEVELOPMENT OF COMPUTATIONAL WEAR PREDICTION ON TOTAL

ANKLE REPLACEMENT

AMIR PUTRA BIN MD SAAD

A thesis submitted in fulfilment of the

requirements for the award of the degree of

Master of Engineering (Mechanical)

Faculty of Mechanical Engineering

Universiti Teknologi Malaysia

JANUARY 2014

iii

Specially dedicated, in thankful appreciation for support, encouragement and

understanding to my lovely wife (Noor Faizah Binti Che Ahmad), my beloved

parents, Mak (Aishah Bt Itam) and Abah (Md Saad Bin Man) and my brother

(Mohd Rizwan Affendi Bin Md Saad).

iv

ACKNOWLEDGEMENT

Praise is to God for everything. He has done to me and bestowing upon me

wisdom, granting me a strong heart and soul throughout this project.

I would like to give my special gratitude to my project supervisors, Dr.

Muhamad Noor Bin Harun, Dr. Ardiyansyah Syahrom and Professor Ir. Dr.

Mohammed Rafiq bin Dato' Abdul Kadir whose encouragement, guidance and

support from the initial to the final level enabled me to develop an

understanding of the project. My supreme thanks to all my fellow friends,

especially on Medical Devices Technology Group (MediTeg) students, and

supportive lecturers from faculty of Mechanical Engineering for their priceless

guidance and encouragement.

Last but not least, I would like to offer my regards and blessings to all of

those who had supported me in any aspect during the completion of this project.

v

ABSTRACT

The computational wear simulation has been widely used to predict wear

generated on hip and knee implant but studies related to wear analysis of the ankle

are limited. The purpose of this study is to develop finite element analysis on total

ankle replacement (TAR) wear prediction. Three-dimensional (3D) models of a right

ankle TAR have been created to represent Bologna-Oxford (BOX) TAR model. The

model consist of three components; tibial, bearing and talar representing their

physiological functions. The joint reaction force profile at ankle joint has applied 25

discrete instants during stance phase of a gait cycle. It is to determine the distribution

of contact stress on meniscal bearing surfaces contact with talar component. The

sliding distance was obtained from predominate motions of plantar/dorsi flexion.

Parametric studies to reduce wear have been conducted to optimize the design of

polyethylene joint. The parameters involved are the thickness of the meniscal

bearing, the radius of curvature between talar and bearing component, the width and

length of meniscal bearing. The value of linear wear depth is 0.01614 mm per

million cycles which is in agreement with other studies (0.0081 – 0.0339 mm per

million cycles). The relative difference is 9%. The value of volumetric wear after

five million cycles is 30.5 mm3 which is in agreement with other studies (16 – 66

mm3). The relative difference is 12%. The best dimension to use for the thickness,

radius of curvature, width and length of meniscal bearing are 6 mm, 30 mm, 30 mm

and 22 mm, respectively.

vi

ABSTRACT

Simulasi pengiraan haus telah digunakan secara meluas untuk meramalkan

haus yang dijana pada implan pinggul dan lutut tetapi kajian yang dilaporkan

berkaitan dengan analisis haus di buku lali adalah sangat terhad. Tujuan kajian ini

adalah membangunkan analisis unsur terhingga untuk meramalkan haus pada

penggantian buku lali (TAR). Model tiga dimensi (3D) buku lali kanan TAR telah

dibangunkan menggunakan penggantian buku lali jenis Bologna-Oxford (BOX).

Model ini terdiri daripada tiga komponen; tibial, bearing dan talar yang mewakili

fungsi fisiologi masing-masing. Beban yang digunakan pada buku lali adalah

berdasarkan profil daya yang bertindak pada buku lali iaitu sebanyak 25 peringkat

berasingan bagi melengkapkan fasa pendirian kitaran gaya berjalan. Ini adalah bagi

menentukan taburan tekanan sentuhan pada permukan meniscal bearing yang

bersentuh dengan komponen talar. Jarak gelungsur telah diperolehi daripada

pergerakan yang paling dominan iaitu plantar/dorsi flexion. Kajian parametrik

dijalankan untuk mengoptimumkan rekabentuk polyethylene di bahagian sendi

terutamanya untuk mengurangkan haus. Parameter yang terlibat ialah ketebalan

meniscal bearing, jejari kelengkungan antara komponen talar dan bearing, lebar dan

panjang meniscal bearing. Nilai kedalaman haus linear adalah 0.01614 mm bagi

setiap satu juta kitaran yang mana ianya berada dalam julat persetujuan dengan

kajian-kajian lain (0.0081 – 0.0339 mm bagi setiap satu juta kitaran) dengan

perbezaan relatif sebanyak 9%. Nilai isipadu kehausan selepas lima juta kitaran

adalah 30.5 mm3 yang mana ianya berada dalam julat persetujuan dengan kajian-

kajian lain (16 – 66 mm3) dengan perbezaan relatif sebanyak 12%. Dimensi terbaik

ketebalan, jejari kelengkungan, lebar dan panjang meniscal bearing adalah masing-

masing sebanyak 6 mm, 30 mm, 30 mm dan 22 mm.

vii

TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION ii

DEDICATION iii

ACKNOWLENFEMENTS iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLE x

LIST OF FIGURES xi

LIST OF ABBREVIATIONS xiv

LIST OF SYMBOLS xv

1 INTRODUCTION 1

1.0 Introduction 1

1.1 Problem Statement 2

1.2 Objectives 4

1.3 Scopes 4

1.4 Importance of the Study 5

2 LITERATURE REVIEW 6

2.1 Introduction 6

2.2 Ankle Joint Anatomy 6

2.2.1 Ankle Biomechanics 9

viii

2.2.1.1 Loading on The Ankle 10

2.2.1.2 Kinematics of The Ankle 13

2.2.2 Ankle Joint Problems Lead to Surgical

Treatment

15

2.2.3 Ankle Joint Treatment 17

2.2.3.1 Ankle Fusion 17

2.2.3.2 Total Ankle Replacement 18

2.3 Total Ankle Replacement (TAR) 20

2.3.1.1 Agility TAR 21

2.3.1.2 Scandinavian TAR (STAR) 22

2.3.1.3 Buechel-Pappas (BP) TAR 23

2.3.1.4 Bologna,Oxford (BOX) TAR 24

2.3.2 Complications 25

2.4 Wear Model 26

2.4.1 Wear of Total Ankle Replacement (TAR) 28

2.4.2 Contact Pressure of Total Ankle

Replacement (TAR)

29

2.5 Summary 30

3 MATERIALS AND METHODS 31

3.1 Introduction 31

3.2 Flowchart 31

3.3 Geometric Model 33

3.4 Finite Element Analysis 34

3.4.1 Development of Finite Element Analysis

on Gait Cycle

35

3.4.1.1 Create Model

3.4.1.2 Define Materials

3.4.1.3 Configure Analysis

3.4.1.4 Apply Loads and Boundary

Conditions

3.4.1.5 Mesh the Model

3.4.1.6 Run Analysis

37

37

37

38

40

41

ix

3.5 Contact Analysis

3.5.1 Sliding Distance

41

43

3.6 Wear Model 44

3.7 Update Contact Geometry 45

3.8 Parametric Studies 48

3.5.1 Thickness of Meniscal Bearing 48

3.5.2 Radius of Curvature of Meniscal Bearing 49

3.5.3 Length and Width of Meniscal Bearing 51

4 RESULT AND DISCUSSION 52

4.1 Validation 52

4.1.1 Mesh Sensitivity Test 53

4.1.2 Contact Analysis 54

4.1.3 Wear Sensitivity Study 56

4.2 Parametric Studies 59

4.2.1 Thickness of Meniscal Bearing 60

4.2.2 Radius of Curvature of Meniscal Bearing 63

4.2.2.1 Unconformable Geometry of

Radius of Curvature of Meniscal

Bearing

67

4.2.3 Length of Meniscal Bearing 69

4.2.4 Width of Meniscal Bearing 73

5 CONCLUSION 76

5.1 Conclusion 76

5.2 Future Work 77

REFERENCES 78

x

LIST OF TABLES

NO. TITLE

PAGE

2.1

2.2

Demographics of lower limb in the hip, knee and ankle

Wear rate for selected TAR

16

29

2.3 Contact pressure of TAR 30

4.1 Mesh sensitivity details 53

xi

LIST OF FIGURE

NO. TITLE PAGE

2.1 Anatomy of the ankle joint 7

2.2 Motions of the ankle joint 8

2.3 Schematic of normal gait 10

2.4 Joint reaction profile at ankle joint 11

2.5 Joint force profile at ankle joint with different subject 12

2.6 Load profile on the ankle joint 13

2.7 Kinematics of the ankle 14

2.8 Patterns of plantar and dorsi flexion during gait 15

2.9 Arthritic ankle joint 16

2.10 Ankle fusion 18

2.11 Modern prosthesis (a) Two component and (b) Three

component

19

2.12 Agility TAR 21

2.13 Position of Scandinavian Total Ankle Replacement (STAR)

prosthesis in ankle joint

22

2.14 Scandinavian Total Ankle Replacement (STAR) prosthesis 23

2.15 Position of Buechel-Pappas® prosthesis in ankle joint 24

2.16 Buechel-Pappas® TAR 24

2.17 Bologna, Oxford (BOX) prosthesis 25

3.1 Flowchart of computational wear prediction simulation 32

3.2 Implant Geometry 33

3.3 General analysis for Finite Element Analysis 35

3.4 Flowchart of finite element analysis of gait cycle 36

xii

3.5 Load and boundary conditions configuration on finite element

simulation model.

39

3.6 Time histories of applied boundary conditions and force

predictions of stance phase.

40

3.7 Geometrical characteristic of TAR model: anatomical

directions (z vertical, x anterior, y medial).

42

3.8

3.9

3.10

3.11

3.12

3.13

Schematic of the sliding distance using plantar/dorsi flexion

angles.

Bearing contact surface between bearing-talar contacts

Adaptive remeshing technique

Thickness of meniscal bearing

Radius of curvature parameter (a) Conformable (b)

Unconformable

Length and width of meniscal bearing location

44

46

47

49

50

51

4.1 A plot of maximum contact pressure versus number of

elements, n shows the changes in contact pressure results for

the different mesh densities.

53

4.2 Contact pressure distributions of the bearing contact surface

between bearing-talar contacts for selected instant of stance

phase of gait cycle.

55

4.3 Maximum linear wear depth of the sensitivity test of different

update interval cycle.

57

4.4 Volumetric wear of the sensitivity test of different update

interval cycle.

58

4.5 Contact pressure distributions of the bearing contact surface

between bearing-talar contacts after one year mesh update (2

million cycles) using 500,000 cycles to update interval for

selected instant of the stance phase of the gait cycle.

59

4.6 Linear wear depth of different thickness of meniscal bearing. 60

4.7 Volumetric wear of different thickness of meniscal bearing 61

4.8 Contour plot of contact pressure of different thickness of

meniscal bearing after 5 million cycles at 80% of the stance

phase of the gait cycle.

62

xiii

4.9 Linear wear depths of different radius of curvature of meniscal

bearing.

63

4.10 Maximum contact pressure curves of different radius of

curvature of meniscal bearing.

64

4.11 Contour plots of contact pressure distribution of different radius

of curvature after 5 million cycles at 80% of the stance phase of

the gait cycle

65

4.12 Volumetric wear of different radius of curvature of meniscal

bearing

66

4.13 Linear wear depths of unconformable geometry and

conformable geometry.

67

4.14 Volumetric of unconformable geometry and conformable

geometry

68

4.15 Contour plots of contact pressure distribution of different

geometry of conformable radius after 5 million cycles at 80%

of the stance phase of the gait cycle

69

4.16

4.17

4.18

4.19

4.20

4.21

Linear wear depth of different length of meniscal bearing

Volumetric wear of different length of meniscal bearing

Contour plots of contact pressure distribution of different length

of meniscal bearing after 5 million cycles at 80% of the stance

phase of the gait cycle.

Linear wear depth of different width of meniscal bearing

Volumetric wear of different width of meniscal bearing

Contour plots of contact pressure distribution of different width

of meniscal bearing after 5 million cycles at 80% of the stance

phase of the gait cycle

69

70

72

73

74

74

xiv

LIST OF ABBEVIATIONS

TAR - Total Ankle Replacement

THR - Total Hip Replacement

TKR - Total Knee Replacement

UHMWPE - Ultra High Molecular Weight Polyethylene

CoCr - Cobalt Chromium

EMG - Electromyography

3D - Three-dimensional

BW - Body Weight

OA - Osteoarthritis

RA - Rheumatoid Arthritis

N - Newton

CAD - Computer-aided design

MPa - Mega Pascal

GPa - Giga Pascal

xv

LIST OF SYMBOLS

ℎ - Linear Wear

�� - Wear Factor

� - Contact Pressure

� - Sliding Distance

υ - Poisson’s ratio

� - Young’s modulus

� - Radius

W - Axial Load

D - Diameter

� - Volumetric Wear

CHAPTER 1

INTRODUCTION

1.0 Introduction

Total ankle replacement (TAR) is an artificial joint that has developed

significantly to replace the arthritic ankle joint. The arthritic or damaged joint

surfaces have removed and replaced with the artificial joint to restore ankle mobility

and stability while performing daily activities. Besides that, there is a therapy

resistant for ankle pain without remove and replaced joint surfaces known as ankle

fusion, also known as arthrodesis. However, the disadvantages of ankle arthrodesis

have led to the development of numerous ankle prostheses. The development of total

ankle replacement (TAR) has lagged behind than the total hip replacement (THR)

and total knee replacement (TKR). However, clinically has shown that the ankle

replacement designs are still not fully satisfactory.

2

1.1 Problem Statement

Arthritis is the main issues that bring an ankle joint to have an operative

(arthrodesis or ankle replacement) or non-operative management (analgesics and

anti-inflammatory medication, activities modification, physiotherapy, orthotics

(bracing) and intra-articular injections) [1,2]. In the ankle joint, primary osteoarthritis

is less frequent but secondary arthritis to trauma occurs is frequent compared with

the knee and hip joint [1]. The earliest treatment of end-stage arthritis of the ankle

joint has been used was arthrodesis, known as ankle fusion, that considered as ‘gold

standard’ treatment for patient suffering from this condition [1,3]. It has becoming

popular to be used because of the arthroscopically assisted and minimally invasive

[1,3,4]. Alternative to arthrodesis is ankle replacement which is for selected patients.

The advantage of ankle replacement using prosthesis is the installation of the

physiologic motion of ankle activity. This will improvise the gait activities which

could also reducing limp and protect the other joints [2]. The major complication

related with failure of ankle replacement is loosening of the component [2,5,6,7].

Aseptic loosening of joint replacement is becoming a crucial factor of total

ankle replacement (TAR) failures and revision. Even the expanding of the

development of joint replacement is impressive and shows promising result. The

main factor that limiting the longevity of total ankle replacement (TAR) is particle

induced osteolysis (bone resoption). Polyethylene wear particles are generated from

relative movement between contacting components (soft-on-hard (SoH)). This wear

particles stimulate an immune response that initiate a cascade of adverse tissue

responses leading to osteolysis and the subsequent loosening of the implant

component [8,9]. The loosen ankle replacement will cause a greater impact to the

patient such as severe pain around the ankle. When this happened, a surgery is

required in order to revise the ankle [9].

3

In a few decades, it has shown that there was a big improvement of design for

the first generation of ankle replacement since 1970s until now. The studies have

been done to come out with the design of TAR, which imitate the natural anatomy of

ankle in order to preserve human movements [10]. The mobile ankle-type has

introduced to perform the physiological ankle mobility. The components of mobile

ankle consist of a spherical convex tibial component, a talar component with radius

of curvature in the sagittal plane longer than that of the natural talus, and a

corresponding meniscal component[11,12,13]. The new generation ankle

replacement is fully conforming, and completely congruence in designs to provide

greater stability and resistance to wear. Other advantage of congruent surfaces is the

load from the body weight acts on the surfaces it is distributes well across the

surfaces. It is led to decreasing wear due to reduce contact pressure [5].

The investigations of wear mechanism of UHMWPE of ankle joint replacement

have reported by means of experimental test. The laboratory study has carried out

using simulators to install originality of realistic loading and kinematics conditions of

the ankle joint. Preoperative in-vitro wear predictions are useful and requires for

implant design optimization of total ankle replacement (TAR). However, it is costly

as well as time consuming. From the best of our knowledge, there is no wear

prediction on total ankle replacement (TAR) by using finite element analysis.

Therefore, the main objective was to develop computational wear simulation of the

total ankle replacement (TAR) for the stance phase of gait cycle.

4

1.2 Objectives

The purpose of this research is to develop a computational wear prediction on

total ankle replacement (TAR). The specific objectives:

i. To develop the total ankle replacements (TAR) wear model.

ii. To validate the linear and volumetric wear predictions with in vitro studies.

iii. To analyse the total ankle wear replacement (TAR) wear model with different

parameters are thickness of meniscal bearing, radius of articular contact,

width and length of meniscal bearing.

1.3 Scopes

1. The three-dimensional (3D) model of total ankle replacement is constructing to

represent Bologna-Oxford (BOX).

2. This study develops the computational work using finite element analysis to

simulate ankle gait analysis. This study will limit to only stance phase of ankle

gait cycle because the swing phase does not give any loads.

3. The computational simulations will perform to extract data of sliding distance

and contact pressure, which is this parameter will include in the wear calculation.

4. Linear wear depths, h and volumetric wear, V of total ankle replacement (TAR)

are important parameters that will analyse in the wear prediction on total ankle

replacement (TAR).

5. The contact geometry of bearing-talar contact will update using adaptive

remeshing techniques until 5 million cycles with appropriate update intervals.

6. This research will continue to perform parametric studies of total ankle

replacement for the design optimization. This parametric studies will covers the

thickness of the meniscal bearing, the radius of the articular contact between

talar and bearing component, the width of meniscal bearing and the length of

meniscal bearing.

5

1.4 Significance of the Study

A major reason of total ankle replacement (TAR) failures and revision is

aseptic loosening. The production of wear debris induces osteolysis that opposes

response of tissue that led to loosening. This study on wear prediction of total ankle

replacement (TAR) using finite element analysis method is an alternativeto solve

ankle replacement complications. Pre-clinical experimental wear testing is very

effective to evaluate new ankle replacement in the aspect of design and material used.

However, both cost and time can be one of the constraints factors, particularly in the

early stage of design or analysis. Therefore, numerical method has been addressed as

an alternative to predict wear on ankle replacement.

78

REFERENCES

[1] D. T. Rhys TH, “Ankle arthritis. Current concepts review.,” J Bone Jt. Surg Am, no. 85A, pp. 923 – 936, 2003.

[2] N. E. Gougoulias, A. Khanna, and N. Maffulli, “History and evolution in total ankle arthroplasty.,” Br. Med. Bull., vol. 89, pp. 111–51, Jan. 2009.

[3] S. D. Jackson MP, “Total ankle replacement,” Curr Orthop, vol. 17, pp. 292 – 298, 2003.

[4] P. S. Gougoulias NE, Aggathangelidis F, “Arthroscopic ankle arthrodesis,” Foot Ankle Int, vol. 28, pp. 695 – 706, 2007.

[5] J. a Vickerstaff, A. W. Miles, and J. L. Cunningham, “A brief history of total ankle replacement and a review of the current status.,” Med. Eng. Phys., vol. 29, no. 10, pp. 1056–64, Dec. 2007.

[6] B. Hintermann, V. Valderrabano, G. Dereymaeker, and W. Dick, “The HINTEGRA Ankle: Rationale and Short-Term Results of 122 Consecutive Ankles,” Clin. Orthop. Relat. Res., vol. 424, 2004.

[7] S. Giannini, M. Romagnoli, J. J. O’Connor, F. Catani, L. Nogarin, B. Magnan, F. Malerba, L. Massari, M. Guelfi, L. Milano, A. Volpe, A. Rebeccato, and A. Leardini, “Early clinical results of the BOX ankle replacement are satisfactory: a multicenter feasibility study of 158 ankles.,” J. Foot Ankle Surg., vol. 50, no. 6, pp. 641–7, 2011.

[8] T. A. Maxian, T. D. Brown, D. R. Pedersen, and J. J. Callaghan, “3-Dimensional Sliding/Contact Computational Simulation of Total Hip Wear,” Clin. Orthop. Relat. Res., vol. 333, 1996.

[9] E. Ingham and J. Fisher, “The role of macrophages in osteolysis of total joint replacement.,” Biomaterials, vol. 26, no. 11, pp. 1271–86, Apr. 2005.

[10] A. Leardini and L. Rapagna, “Computer-assisted preoperative planning of a novel design of total ankle replacement,” vol. 67, pp. 231–243, 2002.

[11] A. Leardini, J. J. O’Connor, F. Catani, and S. Giannini, “Mobility of the Human Ankle and the Design of Total Ankle Replacement,” Clin. Orthop. Relat. Res., vol. 424, 2004.

[12] S. Affatato, a Leardini, W. Leardini, S. Giannini, and M. Viceconti, “Meniscal wear at a three-component total ankle prosthesis by a knee joint simulator.,” J. Biomech., vol. 40, no. 8, pp. 1871–6, Jan. 2007.

79

[13] R. Daud, M. R. Abdul Kadir, S. Izman, A. P. Md Saad, M. H. Lee, and A. Che Ahmad, “Three-Dimensional Morphometric Study of the Trapezium Shape of the Trochlea Tali.,” J. Foot Ankle Surg., pp. 1–6, Apr. 2013.

[14] J. G. Snedeker, S. H. Wirth, and N. Espinosa, “Biomechanics of the normal and arthritic ankle joint.,” Foot Ankle Clin., vol. 17, no. 4, pp. 517–28, Dec. 2012.

[15] A. Hayes, Y. Tochigi, and C. L. Saltzman, “Ankle morphometry on 3D-CT images.,” Iowa Orthop. J., vol. 26, pp. 1–4, Jan. 2006.

[16] K. Watanabe, H. B. Kitaoka, L. J. Berglund, K. D. Zhao, K. R. Kaufman, and K.-N. An, “The role of ankle ligaments and articular geometry in stabilizing the ankle.,” Clin. Biomech. (Bristol, Avon), vol. 27, no. 2, pp. 189–95, Feb. 2012.

[17] J. M. Michael, A. Golshani, S. Gargac, and T. Goswami, “Biomechanics of the ankle joint and clinical outcomes of total ankle replacement.,” J. Mech. Behav. Biomed. Mater., vol. 1, no. 4, pp. 276–94, Oct. 2008.

[18] Y. Tochigi, M. J. Rudert, C. L. Saltzman, A. Amendola, and T. D. Brown, “Contribution of Articular Surface Geometry to Ankle Stabilization,” J. Bone Jt. Surg., vol. 88, no. 12, pp. 2704–2713, Dec. 2006.

[19] R. Donatelli, “Normal Biomechanics of the Foot and Ankle,” pp. 91–95, 1985.

[20] A. Seireg and R. J. Arvikar, “The prediction of muscular load sharing and joint forces in the lower extremities during walking,” J. Biomech., vol. 8, no. 2, pp. 89–102, Mar. 1975.

[21] R. N. Stauffer, E. Y. Chao, and R. C. Brewster, “Force and motion analysis of the normal, diseased, and prosthetic ankle joint,” Clin Orthop Relat Res, no. 127, pp. 189–196, 1977.

[22] Procter P and Paul JP, “Ankle Joint biomechanics.” J. Biomech, pp. Vol 15, pp627–634, 1982.

[23] B. Reggiani, a Leardini, F. Corazza, and M. Taylor, “Finite element analysis of a total ankle replacement during the stance phase of gait.,” J. Biomech., vol. 39, no. 8, pp. 1435–43, Jan. 2006.

[24] G. Bergmann, G. Deuretzbacher, M. Heller, F. Graichen, a Rohlmann, J. Strauss, and G. N. Duda, “Hip contact forces and gait patterns from routine activities.,” J. Biomech., vol. 34, no. 7, pp. 859–71, Jul. 2001.

[25] L. W. Lamoreux, “Kinematic Measurements in The Study of Human,” Bull. Prosthet. Res., vol. 10(15), no. 3–84, pp. pp.3–84.

[26] P. F. Calderale PM, Garro A, Barbiero R, Fasolio G, “Biomechanical design of the total ankle prosthesis,” Eng. Med., vol. Vol 2, p. pp69, 1983.

80

[27] Y. S. Conti, S.F., Wong, “Complications of total ankle replacement,” Clin. Orthop. Relat. Res., vol. 391, pp. 105–114, 2001.

[28] LLC, “Arthritic Ankle Joint,” Med. Multimed. Gr., 2001.

[29] F. G. Krause and T. Schmid, “Ankle arthrodesis versus total ankle replacement: how do I decide?,” Foot Ankle Clin., vol. 17, no. 4, pp. 529–43, Dec. 2012.

[30] C. J. Bell and J. Fisher, “Simulation of Polyethylene Wear in Ankle Joint Prostheses,” no. October 2005, pp. 162–167, 2006.

[31] C. L. Saltzman, T. E. McIff, J. a Buckwalter, and T. D. Brown, “Total ankle replacement revisited.,” J. Orthop. Sports Phys. Ther., vol. 30, no. 2, pp. 56–67, Feb. 2000.

[32] A. Karantana, S. Hobson, and S. Dhar, “The scandinavian total ankle replacement: survivorship at 5 and 8 years comparable to other series.,” Clin. Orthop. Relat. Res., vol. 468, no. 4, pp. 951–7, Apr. 2010.

[33] M. S. Ali, G. a Higgins, and M. Mohamed, “Intermediate results of Buechel Pappas unconstrained uncemented total ankle replacement for osteoarthritis.,” J. Foot Ankle Surg., vol. 46, no. 1, pp. 16–20, 2005.

[34] S. Ingrosso, M. G. Benedetti, a Leardini, S. Casanelli, T. Sforza, and S. Giannini, “GAIT analysis in patients operated with a novel total ankle prosthesis.,” Gait Posture, vol. 30, no. 2, pp. 132–7, Aug. 2009.

[35] a Leardini, J. O’Connor, F. Catani, M. Romagnoli, and S. Giannini, “Preliminary results of a biomechanics driven design of a total ankle prosthesis,” J. Foot Ankle Res., vol. 1, no. Suppl 1, p. O8, 2008.

[36] D. Singh, “Total ankle replacement,” vol. 0890, pp. 292–298, 2003.

[37] F. Liu, a Galvin, Z. Jin, and J. Fisher, “A new formulation for the prediction of polyethylene wear in artificial hip joints,” Proc. Inst. Mech. Eng. Part H J. Eng. Med., vol. 225, no. 1, pp. 16–24, Jan. 2011.

[38] J. F. Archard, “Contact and Rubbing of Flat Surfaces,” J. Appl. Phys., vol. 24, no. 8, p. 981, 1953.

[39] P. Po, “Wear simulation with the Winkler surface model Priit Po,” vol. 207, pp. 79–85, 1997.

[40] a Buford and T. Goswami, “Review of wear mechanisms in hip implants: Paper I – General,” Mater. Des., vol. 25, no. 5, pp. 385–393, Aug. 2004.

[41] T. M. McGloughlin, D. M. Murphy, and a G. Kavanagh, “A machine for the preliminary investigation of design features influencing the wear behaviour of

81

knee prostheses,” Proc. Inst. Mech. Eng. Part H J. Eng. Med., vol. 218, no. 1, pp. 51–62, Jan. 2004.

[42] L. A. Knight, S. Pal, J. C. Coleman, F. Bronson, H. Haider, D. L. Levine, M. Taylor, and P. J. Rullkoetter, “Comparison of long-term numerical and experimental total knee replacement wear during simulated gait loading,” J. Biomech., vol. 40, no. 7, pp. 1550–1558, 2007.

[43] S. Carmignato, M. Spinelli, S. Affatato, and E. Savio, “Uncertainty evaluation of volumetric wear assessment from coordinate measurements of ceramic hip joint prostheses,” Wear, vol. 270, no. 9–10, pp. 584–590, Apr. 2011.

[44] C. Fabry, S. Herrmann, M. Kaehler, E.-D. Klinkenberg, C. Woernle, and R. Bader, “Generation of physiological parameter sets for hip joint motions and loads during daily life activities for application in wear simulators of the artificial hip joint.,” Med. Eng. Phys., vol. 35, no. 1, pp. 131–9, Jan. 2013.

[45] a. L. L. Oliveira, R. G. Lima, E. G. Cueva, and R. D. Queiroz, “Comparative analysis of surface wear from total hip prostheses tested on a mechanical simulator according to standards ISO 14242-1 and ISO 14242-3,” Wear, vol. 271, no. 9–10, pp. 2340–2345, Jul. 2011.

[46] V. Saikko and O. Calonius, “Simulation of wear rates and mechanisms in total knee prostheses by ball-on-flat contact in a five-station, three-axis test rig,” Wear, vol. 253, no. 3–4, pp. 424–429, Aug. 2002.

[47] C. M. Goreham-Voss, P. J. Hyde, R. M. Hall, J. Fisher, and T. D. Brown, “Cross-shear implementation in sliding-distance-coupled finite element analysis of wear in metal-on-polyethylene total joint arthroplasty: intervertebral total disc replacement as an illustrative application.,” J. Biomech., vol. 43, no. 9, pp. 1674–81, Jun. 2010.

[48] M. S. Uddin and L. C. Zhang, “Predicting the wear of hard-on-hard hip joint prostheses,” Wear, vol. 301, no. 1–2, pp. 192–200, Apr. 2013.

[49] A. C. Cilingir, “Finite Element Analysis of the Contact Mechanics of Ceramic-on-Ceramic Hip Resurfacing Prostheses,” J. Bionic Eng., vol. 7, no. 3, pp. 244–253, Sep. 2010.

[50] L. Mattei, F. Di Puccio, and E. Ciulli, “A comparative study of wear laws for soft-on-hard hip implants using a mathematical wear model,” Tribol. Int., vol. 63, pp. 66–77, Jul. 2013.

[51] M. Noor and H. Faculty, “Long-Term Contact-Coupled Wear Prediction for Total Metal-on-Metal Hip Joint Replacement,” pp. 835–836.

[52] P. D. Postak and A. S. Greenwald, “EVALUATION OF A MOBILE BEARING TOTAL ANKLE REPLACEMENT IN,” 2009.

82

[53] M. C. Miller, P. Smolinski, S. Conti, and K. Galik, “Stresses in Polyethylene Liners in a Semiconstrained Ankle Prosthesis,” J. Biomech. Eng., vol. 126, no. 5, p. 636, 2004.

[54] M. M. Nicholson JJ, Parks BG, Stroud CC, “Joint contact characteristics in agility total ankle arthroplasty,” Clin Orthop Relat Res, vol. (424), pp. 125–9.

[55] Z. L. Fukuda T, Haddad SL, Ren Y, “Impact of talar component rotation on contact pressure after total ankle arthroplasty: a cadaveric study,” Foot Ankle Int, vol. 31(5), pp. 404–11.

[56] B. T. McIff TE, Saltzman C, “Contact pressure and internal stresses in a mobile bearing total ankle replacement,” 45th Annu. Meet. Orthop. Res. Soc. San Fr. CA, pp. 25–28.

[57] a Leardini, J. O’Connor, F. Catani, M. Romagnoli, and S. Giannini, “Preliminary results of a biomechanics driven design of a total ankle prosthesis,” J. Foot Ankle Res., vol. 1, no. Suppl 1, p. O8, 2008.

[58] F. C. Wang, Z. M. Jin, H. M. J. McEwen, and J. Fisher, “Microscopic asperity contact and deformation of ultrahigh molecular weight polyethylene bearing surfaces,” Proc. Inst. Mech. Eng. Part H J. Eng. Med., vol. 217, no. 6, pp. 477–490, Jun. 2003.

[59] A. Ianuzzi and C. Mkandawire, Applications of UHMWPE in Total Ankle Replacements, Second Edi. Elsevier Inc., 2006, pp. 153–169.

[60] S. De and N. Engineering, “Abaqus Handout.”

[61] a C. Godest, M. Beaugonin, E. Haug, M. Taylor, and P. J. Gregson, “Simulation of a knee joint replacement during a gait cycle using explicit finite element analysis.,” J. Biomech., vol. 35, no. 2, pp. 267–75, Feb. 2002.

[62] M. T. Raimondi, C. Santambrogio, R. Pietrabissa, F. Raffelini, and L. Molfetta, “Improved mathematical model of the wear of the cup articular surface in hip joint prostheses and comparison with retrieved components,” Proc. Inst. Mech. Eng. Part H J. Eng. Med., vol. 215, no. 4, pp. 377–390, Apr. 2001.

[63] S. G. Lundberg A, Goldie I, Kalin B, “Kinematics of the ankle/foot complex - Part 1: Plantarflexion and dorsiflexion.,” Foot Ankle, vol. 9, pp. 194–200, 1989.

[64] J. Fisher, Z. Jin, J. Tipper, M. Stone, and E. Ingham, “PRESIDENTIAL GUEST LECTURE: Tribology of Alternative Bearings,” Clin. Orthop. Relat. Res., vol. 453, 2006.

[65] S. M. Bouchard, K. J. Stewart, D. R. Pedersen, J. J. Callaghan, and T. D. Brown, “Design factors influencing performance of constrained acetabular liners: finite element characterization.,” J. Biomech., vol. 39, no. 5, pp. 885–93, Jan. 2006.

83

[66] J. a Mann, R. a Mann, and E. Horton, “STARTM ankle: long-term results.,” Foot Ankle Int., vol. 32, no. 5, pp. S473–84, May 2011.

[67] K. H, “Scandinavian Total Ankle Replacement (STAR),” Clin Orthop Relat Res, vol. (424), pp. 73–9.

[68] M. Bonnin, T. Judet, J. a Colombier, F. Buscayret, N. Graveleau, and P. Piriou, “Midterm Results of the Salto Total Ankle Prosthesis,” Clin. Orthop. Relat. Res., vol. 424, no. 424, pp. 6–18, Jul. 2004.

[69] M. Grosland, D. Ph, D. R. Pedersen, and T. P. Thomas, “Analysis as a Metric of Degeneration Propensity,” vol. 5, no. 319, pp. 82–89, 2008.

[70] T. P. Schmalzried, E. F. Shepherd, F. J. Dorey, W. O. Jackson, M. dela Rosa, F. Fa’vae, H. A. McKellop, C. D. McClung, J. Martell, J. R. Moreland, and H. C. Amstutz, “Wear Is a Function of Use, Not Time,” Clin. Orthop. Relat. Res., vol. 381, 2000.